夏季臺灣地區大規模瞬變渦流之動量可感熱能及水氣傳播

Westerly Momentum, Sensible Heat and Moisture Fluxes by Large Scale Transient Eddies in Taiwan Area: Summer Season

張利雄

《大氣科學》 9卷1期 (1982/05) Pp. 67-82

摘要

臺灣地區夏季對流層內綜觀規模天氣擾動所造成之西風動量，可感熱能及水汽之渦動傳播均以南北向擾動分風與各個對應變數之同變量來估計。而兩天至兩週為週期之各波頻擾動對整體同變量之貢獻則以彼等之同波譜對各頻帶之積分來表示。於1970至1972連續三年在各等壓面之分析結果顯示臺灣地區夏季對流層內上述三量之經向傳播，大致趨勢以由南向北為主，即動量渦動傳播以逆梯度方向，而可感熱與水汽則以順梯度之方向進行，此種傳送方式為副熱帶緯度所應有者，渦動傳播量以200mb附近達到最大。上述之渦動流通量主要貢獻來自七至十天為週期之擾動；另一貢獻區間以四至五天為週期，後者只發生於1971年夏季臺灣地區之低對流層850 mb附近，三種渦動傳播皆以向赤道之方向進行，此型態頗類似於低緯度之熱帶波動者，顯示此年夏季西太平洋熱帶波動之影響到達台灣地區，是年侵臺灣之颱風統計亦顯示稍多於前後之年代。

並列摘要

Tutbulent fluxes of westerly momentum, sensible heat and water vapor due to large scale transient eddies have been estimated by the covariances between the perturbation meridional wind component and the respective fluctuating quantities. Total turbulent transprts and partial contributions by specific frequency bands are computed through summations of cospectra estimates over the frequency bands.Computaions of these eddy fluxes within the troposphere in Taiwan area for three consecutive years (1970-1972) show a general picture of poleward fluxes. A major contribution to turbulent fluxes comes from the frequency band of 7-10 days in period in this subtropical region. Besides, for 1971 summer, the 4-5 day s disturbance plays a significant role in these eddy fluxes at 850 mb level. The transport is southward. It is similar to those a t lower tropical latitudes in Western Pacific, This may be an indication of the intrusion of tropicaI wave disturbances into this region. Further statistics may be necessary to confirm this speculation.